With the advent of digital communications technology, many TV program streams are transmitted in digital formats. For example, Digital Satellite System (DSS), Digital Broadcast Services (DBS), and Advanced Television Standards Committee (ATSC) program streams are digitally formatted pursuant to the well known Moving Pictures Experts Group 2 (MPEG-2) standard. The MPEG-2 standard specifies, among other things, the methodologies for video and audio data compression allowing for multiple programs, with different video and audio feeds, to be multiplexed in a transport stream traversing a single transmission channel. A digital TV receiver may be used to decode an MPEG-2 encoded transport stream, and extract the desired program therefrom.
The compressed video and audio data are typically carried by continuous elementary streams, respectively, which are broken into access units or packets, resulting in packetized elementary streams (PESs). These packets are identified by headers that contain time stamps for synchronizing, and are used to form MPEG-2 transport streams. For digital broadcasting, multiple programs and their associated PESs are multiplexed into a single transport stream. A transport stream has PES packets further subdivided into short fixed-size data packets, in which multiple programs encoded with different clocks can be carried. A transport stream not only includes a multiplex of audio and video PESs, but also other data such as MPEG-2 program specific information (sometimes referred to as metadata) describing the transport stream. The MPEG-2 metadata may include a program associated table (PAT) that lists every program in the transport stream. Each entry in the PAT points to an individual program map table (PMT) that lists the elementary streams making up each program. Some programs are open, but some programs may be subject to conditional access (encryption), and this information (i.e., whether open or subject to conditional access) is also carried in the MPEG-2 transport stream, typically as metadata.
The aforementioned fixed-size data packets in a transport stream each carry a packet identifier (PID) code. Packets in the same elementary streams all have the same PID, so that a decoder can select the elementary streams(s) it needs and reject the remainder. Packet-continuity counters may be implemented to ensure that every packet that is needed to decode a stream is received.
Video on demand (VOD) systems allow users to select and watch video content over a network. Some VOD systems “stream” content for real-time viewing. Others “download” the content to a set-top box before viewing starts. Use of digital video recorders (DVRs), also known as personal video recorders (PVRs), such as the TiVo® device (registered mark of TiVo Brands LLC, Alviso, Calif.) and the R Replay TV® device (registered mark of Digital Networks North America Inc., Pine Brook, N.J.), is ubiquitous. Such devices may provide some benefits to TV viewers. For example, a prior art DVR allows a user to record his or her favorite TV programs for later review, and to exercise a season-pass-like option wherein every episode of his or her favorite program is recorded for some period. Such devices may automatically record programs for the user based on his or her viewing habits and preferences. The presentation of the recorded programming content can be manipulated by exercising rewind, pause, skip and/or fast-forward functions (hereinafter referred to as “trick mode” or “trick play” functions) furnished by the DVR.
U.S. Pat. No. 7,073,189 of McElhatten, et al. is entitled “Program guide and reservation system for network based digital information and entertainment storage and delivery system.” The disclosure of the aforesaid U.S. Pat. No. 7,073,189 of McElhatten, et al. is expressly incorporated herein by reference in its entirety for all purposes. A “network PVR (NPVR)” (also referred to as an NDVR (Network Digital Video Recorder)) service allows the user to perform the analogous DVR functions through use of a network, rather than via a local DVR at the user premises. Unlike a DVR device, the NPVR service allows a user to “reserve” past and future programs for his or her review, even if such reserved programs were not identified by the user before their broadcast.
Note that an NDVR can be distinguished from a DVR in that the latter, storage of programs and the like is local to the DVR, while in the former (NDVR) case, such storage is at the server or head end level.
US Patent Publication 2004/0103429 A1 of Carlucci et al. is entitled “Technique for delivering entertainment programming content including commercial content therein over a communications network.” The disclosure of the aforesaid US Patent Publication 2004/0103429 A1 of Carlucci et al. is expressly incorporated herein by reference in its entirety for all purposes. The Carlucci et al. publication discloses that although personal video recorders (also known as digital video recorders) provide certain conveniences to viewers of programming content, such devices facilitate manipulation or “skipping” of commercials, frustrating the intent of the advertisers of the commercials. In accordance with the Carlucci et al. invention, when a user fast-forwards (or rewinds) a commercial, alternate commercial(s) may be accessed for display in place of the original commercial, which provides a full impression of the goods and service promoted, otherwise impossible to appreciate at the fast-forward (or rewind) speed. The duration of the alternate commercial(s) corresponds to the duration of the original commercial at the fast-forward (rewind) speed controlled by the user. With the Carlucci et al. invention, the user advantageously realizes the convenience of manipulating programming content, and at the same time can appreciate the full impression of an alternate commercial to the original commercial, albeit in a shorter duration.
US Patent Publication 2005/0060745 A1 of Riedl et al. is entitled “System and method for advertisement delivery within a video time shifting architecture.” The disclosure of the aforesaid US Patent Publication 2005/0060745 A1 of Riedl et al. is expressly incorporated herein by reference in its entirety for all purposes. The Riedl et al. publication discloses systems and methods for creating a program for delivery to a client in a video time shifting architecture. The system of the Riedl et al. invention includes an advertisement selection system (ADS) operative to select one or more advertisements and transmit one or more identifiers that uniquely identify the selected advertisements and an advertisement management system (AMS) operative to generate a playlist that identifies content. The playlist includes a user requested time shifted program and the one or more selected advertisements. A video server is operative to interpret the playlist and deliver the content to the user.